This invention relates to a method and apparatus for broaching elongate work parts and especially to what is termed "blind spline" broaching utilizing multiple broaching rams in the same machine with cutting tools mounted on the rams and having work parts mounted in work holding devices indexed below the rams, rotationally or longitudinally for broaching in a series of passes. U.S. Pat. No. 4,401,406 to Roseliep (1983) discloses a method and apparatus for blind spline broaching.
In previous machines the parts have been mounted in work holding devices attached to rams and the cutting tools mounted to an indexing unit below the work holding rams for the insertion and withdraw of the part. These machines have utilized one or two rams per machine.
The invention to be described is designed to materially improve production. That is, piece output per hour, and incorporates simplified loading and unloading which contributes to the increased productivity. For example, a part requiring six cuts to complete the part in a conventional machine has required almost 30 seconds for a total cycle whereas it is intended that the machine to be described will require less than 5 seconds for a total cycle regardless of the number of cuts.
A patent to Groene et al, U.S. Pat. No. 2,280,229 (1942) shows indexing crankshafts for combination broaching and shaving operation at various indexing stations. U.S. Pat. No. 4,432,130 to Gabriele (1984) illustrates sequentially machining parallel surfaces in workpieces mounted on an indexing table. A patent to Bishop, U.S. Pat. No. 4,193,722, illustrates an in-line operation with spaced apart broach blades.
The present invention to be disclosed utilizes an indexing table having a number of work holding stations which are mounted on a base circle and with spacing equal to the broaching rams described below. While the table may be lineal, it will be described in the present disclosure as a rotatable indexing table. Above the indexing table in positions to register with the work holding stations are broaching rams each holding a broaching tool. These tools will take progressive cuts as described in the above referenced Roseliep patent. The broach tool rams can be power actuated simultaneously, or, in a more economical machine, sequentially.
The indexing of the workpieces with an individual workpiece loading station and a separate unloading station together with the progressive cuts in the blind spline operation allows rapid handling of parts and an extremely efficient and accurate processing of parts in an otherwise difficult machining function.
While the process and apparatus to be described has particular reference to the blind spline cutting, it may also be used in forming similar shapes such as cams or irregular profiles.
Other objects and features of the invention will be apparent in the following description and claims in which the principles of the invention are set forth together with details to enable persons skilled in the art to practice the invention all in connection with the best mode presently contemplated for the invention.